Magnetic or magnetizable composite product and a method for making and using same

ABSTRACT

Thin, flexible composite materials, which are magnetic or magnetizable and processes for producing and using the materials. The composite material contains a laminate formed from a mixture of magnetic or magnetizable particles, binder particles (and optionally active particles), applied to and fused and/or coalesced with a first substrate. The composite preferably contains an additional second substrate fused to and/or coalesced with, the laminate on the side of the laminate opposite that of the first substrate.

BACKGROUND OF THE INVENTION

[0001] I. Field of the Invention

[0002] This invention generally relates to a composite material having amagnetic or magnetizable function. More particularly, this inventionrelates to novel composite materials that are magnetizable, magnetic,has magnetic properties, or any combination thereof.

[0003] II. Description of the Art

[0004] There is a need for providing a magnetic surface to shelves,drawers, walls, partitions and cabinets to support magnets that holddisplays, papers, diagrams, pins, stickers or other objects. Inaddition, it is often desirable to have thin, flexible, ferro-magneticor magnetizable (hereinafter collectively referred to as “magnetic”)sheets or plies that can be employed in a variety of situations.

[0005] However, such magnetic sheets are typically non-porous and/orsubstantially metallic. Thus, there exists a need for improved magneticsheets or plies that can be porous and substantially non-metallic, andmethods for manufacturing such magnetic sheets or plies.

SUMMARY OF THE INVENTION

[0006] The present invention provides for a magnetic or magnetizablecomposite material having a first substrate and a laminate or bondedmixture of magnetizable or magnetic particles and binder particles. Thebinder particles are preferably on average smaller than the magnetizableor magnetic particles, and at least some of the binder particlescoalesce at least some of the magnetizable or magnetic particles to eachother, and to the first substrate.

[0007] In addition, the above composite may further have a plurality ofadditional active particles, in addition to the magnetizable or magneticparticles, that perform a suitable function. The active particles may beany suitable particle that performs a suitable function including, butnot limited to, adsorbent particles, absorbent particles, particles thatrelease liquid or gas held therein, biologically active particles, andthe like.

[0008] Also, the present invention provides for the above compositehaving a second substrate located such that the laminate is between thefirst substrate and the second substrate, wherein at least some of themagnetizable or magnetic particles are coalesced by the binder particlesto each other, to the first substrate, and/or to the second substrate.

[0009] The present invention further provides for a method for producingthe above composite having the steps of applying a mixture ofmagnetizable or magnetic particles and binder particles to a substrate,applying heat to the mixture on the substrate, and applying pressure tothe mixture and the substrate such that the binder particles coalescethe magnetizable particles to themselves, and to the substrate.

[0010] Accordingly, there is provided for a thin, flexible compositematerial, which is magnetizable, and can be magnetic or made magnetic.The composite material of the present invention may be used by placingit upon an outer or inner functional surface such as a shelf, a drawer,a cabinet, a wall or wall panel, a display board, or a room dividingpartition.

BRIEF DESCRIPTION OF THE FIGURES

[0011]FIG. 1 is a cross-sectional view of a preferred embodiment of themagnetizable or magnetic composite of the present invention.

[0012]FIG. 2 is a schematic diagram illustrating an apparatus andprocess for making the magnetizable or magnetic composite of the presentinvention.

[0013]FIG. 3 is a cross-sectional view of a composite material of thepresent invention in contact with a surface.

[0014]FIG. 4 is a schematic diagram illustrating an apparatus andprocess for making a highly oriented magnetic composite materialaccording to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0015] Referring to the drawings, and in particular FIG. 1, there isprovided a magnetizable or magnetic composite generally indicated as 1.The composite 1 has a first substrate or backing layer 6 and optionallya second substrate sometimes referred to as a covering layer or topsheet 7. First substrate 6 and second substrate 7 may be formed ofvarious materials depending upon the intended application and need notbe formed of the same or similar material within one composite. By wayof example only, substrates 6 and/or 7 may be permeable materials, suchas non-woven fibrous webs, e.g., spun bonded, melt blown or cardedmaterials composed of polyester or polyolefinic fibers. The substratesmay also be formed from woven materials. Substrates 6 and/or 7 mayoptionally be formed wholly or in part from cellulosic materialsincluding tissue or towel stock. In the alterative, substrates 6 and/or7 may be either semi-permeable or impermeable to liquids, e.g., apolymeric film, metal foil, metal mesh or the like.

[0016] Coalesced with first substrate 6, and optionally with secondsubstrate 7, is a magnetizable or magnetic laminate or bonded mixtureindicated generally as laminate 2. Laminate 2 has magnetizable ormagnetic particles (hereinafter magnetic particles) 3 and binderparticles 4. The binder particles 4 coalesce at least some of themagnetic particles 3. An amount of binder particles 4 also coalesce atleast some of the magnetic particles 3 to substrate 6, and optionally tosubstrate 7, or to both substrates 6 and 7.

[0017] Magnetic particles 3 may be formed from any suitable magnetic ormagnetizable material. Preferably, magnetic particles 3 containferromagnetic material, magnetizable material, or a combination thereof.In other words, the magnetic particles 3 may have magnetic properties sothat a magnetic or magnetizable structure or substance, external to thatof composite 1, would be attracted to the material. In this regard,there are three possibilities. Composite 1 may be magnetic, the externalstructure or substrate may be magnetic, or both may be magnetic.

[0018] Thus, the magnetic particles 3 may also be magnetizable, that ismay of a material that can be made to be magnetic such as iron or steel.Examples include stainless steel of the 400 series such as 410 stainlesssteel. Further, while much more expensive, other material such as rareearth magnetic media can be used for very specialized applications, thecost of such materials is prohibitive for most applications, but the useof such materials should be considered as encompassed within the scopeof the invention.

[0019] Magnetic particles 3 may have an average particle size from about5 microns to about 5000 microns, preferably from about 100 microns toabout 1000 microns.

[0020] Optionally, laminate 2 can contain other suitable activeparticles 8 in addition to magnetic particles 3. Suitable activeparticles 8 may be any particle that performs a suitable functionincluding, but not limited to, adsorbent particles, absorbent particles,biologically active particles, and the like. Furthermore, activeparticles 8 may be used to release a suitable fluid or a suitable gasheld therein. Such a fluid or gas includes but is not limited to a:lubricant, herbicide, pesticide, insecticide, fungicide, fragrance,humectant, desiccant, antimicrobial agent, malodor absorbing agent,biologically active agent, dye, indicator, and a combination thereof.

[0021] Suitable active particles 8 also include, but are not limited to:iodinated resin, activated carbon, activated alumina, non-magnetic metalpowder, alumina-silicate, super absorbent polymer, metal oxide, zeolite,glass bead, ceramic, diatomaceous earth, macroporous polymer, aerogel,cellulosic material, antimicrobial agent, fragrance, fragrant material,glass micro fiber, titanate micro fiber, starch, foamed polymerabsorbent, macroporous super absorbent polymer, macroreticulate superabsorbent polymer, expanded vermiculite (perlite), carbon, anionexchange resin, cationic exchange resin, protein solid, organic acid,inorganic acid, mineral, salts of an organic acid, salts of an inorganicacid, acrylic based polymer, clay, metal oxihydrate, talcum, silicicacid, metal hydroxide, modified cellulose, cellulose, dye, indicator,liquid absorbing compound, malodor absorbing agent, molecular sieve,phosphate, biologically active agent, and a combination thereof.Biologically active agents can be biocides such as silver-impregnatedzeolites or aluminas or organic or inorganic materials to controlmicrobiological contamination.

[0022] The active particles 8 may also be coated with, impregnated with,or a combination thereof, a suitable active agent. Suitable activeagents include, for example: fluid, lubricant, herbicide, insecticide,pesticide, biocide, fungicide, fragrance, humectant, desiccant,antimicrobial agent, malodor absorbing agent, biologically active agent,dye, indicator, and a combination thereof.

[0023] Active particles 8 have an average particle size from about 5microns to about 5000 microns, preferably from about 100 microns toabout 1000 microns.

[0024] Any suitable binder material may be employed in this invention.Materials suitable for forming binder particles 4 include thermoplasticbinders and thermoset resin binders. As used herein, the term“thermoplastic binder” means any binder, typically a polymer, which isthermoplastic, i.e., capable of softening and flowing when heated and ofhardening again when cooled. Preferred binder materials include,polyethylene, polypropylene, poly (ethylene vinyl acetate), and nylon.

[0025] Preferably, binder particles 4 are present in such an amount andat such a size that they do not substantively interfere with thefunctioning of magnetic particles 3, and optionally with activeparticles 8. Binder particles 4 preferably have an average size of about5 microns to about 100 microns. In addition, binder particles 4 aregenerally significantly smaller in average size than magnetic particles3, and optionally the average size of active particles 8. Morepreferably, binder particles 4 are about 4 to 25 times smaller, onaverage, than the average size of magnetic particles 3, optionally theaverage size of active particles 8.

[0026]FIG. 2 illustrates an exemplary apparatus used to produce thisinvention. A supply roll 10 provides a first substrate 12. Downstreamfrom supply roll 10 is a knurled roller 13 positioned to receive amixture of magnetic particles 3, optionally active particles 8 andbinder particles 4, generally indicated as mixture 14, from hopper 16.Mixture 14 is applied to the upper surface of substrate 12 as acontinuous coating or, alternatively, as a coating in a specific designincluding, but not limited to, stripes. A brush 18 may be employed toaid in removing mixture 14 from knurled roller 13.

[0027] Thereafter, substrate 12 containing mixture 14 is passed throughnip 20 between a heated idler roller 22 and a drive roller 24.Alternatively, before being passed through nip 20, substrate 12containing mixture 14, may be preheated by a pre-heater 50 such as, forexample, a convection or infrared oven, or other suitable heatingsource. A pneumatic cylinder 26 is connected via a rod 28 to the axle ofidler roller 22 to maintain a desired pressure on substrate 12containing mixture 14 within nip 20. In passing through pre-heater 50,and over the surface of heated roller 22, mixture 14 is heated to atemperature equal to or greater than the softening temperature of binderparticles 4, but to a temperature below the softening temperature ofmagnetic particles 3, and optionally below the softening temperature ofactive particles 8. Within nip 20, softened binder particles 4 coalesceunder pressure with magnetic particles 3, and optionally with activeparticles 8. A portion of binder particles 4 coalesce with firstsubstrate 12.

[0028] When magnetizable particles 3 are used, the particles may bemagnetized once applied to substrate 12 by passing the mixture through asuitable magnetizing means 55 and/or 55′ which provide a magnetic fieldof sufficient intensity to magnetize particles 3. Magnetizing means 55and/or 55′ may be located prior to, or after nip 20, or may be locatedindependent of the entire production apparatus. Alternatively,pre-magnetized particles may be used, the particles being caused toassume a more or less uniform orientation by magnetizing means 55 and/or55′. In addition, if magnetizable particles 3 are used, it is possibleto magnetize particles 3, at a later time, after processing of the typeillustrated in FIG. 2. In this latter case, the presence of amagnetizing means 55 and/or 55′ is not immediately required.

[0029] Furthermore, in a preferred embodiment of the present invention,as illustrated in FIG. 2, a second supply roll 30 of a second substrate32, which may be of the same or may be of a different material from thatof substrate 12, is also passed between nip 20 on the top of mixture 14.An amount of binder particles 4 coalesce with second substrate 32. Uponleaving nip 20, binder particles 4 cool and harden. The finishedcomposite 34 then passes onto take-up roll 36.

[0030] By selection of substrate materials 12 and 32, binder materials4, magnetic materials 3, optionally active particles 8, magneticparticles to binder weight ratios, absolute amounts of mixture 14applied to substrate 12 per unit area, binder particle size, magneticparticle size, the ratio of binder particle size to magnetic particlesize, as well as by adjusting the operating conditions, including, butwithout limitation, heating temperature, nip pressure and the linearspeed of substrate 12, it is possible to vary composite depth, porosity,permeability, tensile strength, flexibility, pleatability, drapingability, magnetic strength, and other attributes of the magneticcomposite of the present invention.

[0031] As shown in FIG. 3, composite material 1 may be used on, under,on the side of, or aligned with any suitable surface 9, which is shownas being horizontal, but may also be a vertical surface, and mayinclude, for example, a shelf, a drawer, a cabinet, and/or an inside oroutside surface of a refrigerator. Preferably, composite material 1, dueto the magnetic properties of laminate 2, is magnetically attached to ametal surface 9. Optionally, composite material 1 may be attached to, orcombined with any suitable surface 9 by any suitable method. Forexample, composite material 1 may be fused, glued, tacked, stapled,chemically adhered, mechanically adhered, hooked, sewn, or otherwisejoined with suitable surface 9. Alternatively, composite material 1 maybe placed in direct proximity with suitable surface 9 without a bond ormechanical fastener. Common uses for composite material 1 include, forexample, portable utility magnets, bulletin and message boards,calendars, signs, decorations, and games. Furthermore, magneticcomposite 1 may be used on room dividers, partitions, and walls, such asthose in office cubicles for easy posting of documents therein bymagnetization, while retaining the ability to accept tacks and staples.In this regard reference is made to U.S. Pat. Nos. 5,295,342 and5,384,999 which teach display boards, panels and wall sections of thisgeneral type.

[0032] In addition to metallic or magnetic particles, a magnetizable ormagnetic expanded metal foil or flexible metal mesh or metal screen maybe incorporated into the composite as first substrate 6, secondsubstrate 7, or both substrates. This foil, screen, or mesh could bemagnetized by any common method known in the art, either before, during,or after incorporation into the composite of the present invention.

[0033] Another feature of composite material 1 is that the thermoplasticand/or thermoset binder particles preferably impart a measure offlowability. For example, small holes made in composite 1 by a needle ora tack will generally seal themselves once the needle or tack is removedfrom composite 1. Thus, composite 1 is preferably not only thin andflexible, but also resilient and self-healing.

[0034] Referring to FIG. 4, there is illustrated a schematic of aprocess for producing a highly oriented magnetic composite material.Using a process similar to that described in U.S. Pat. No. 5,792,513herein incorporated by reference in its entirety, magnetic particles 3,and optionally active particles 8, are applied along with the binderparticles 4 to substrate 12 to form a homogeneous layer on substrate 12.A magnetic orienting means 40, such as, by way of example and not by wayof limitation, a magnet or a suitable electromagnet, positioned inproximity to substrate 12 causes the magnetic particles 3 to becomeoriented with the magnetic field lines created by magnetic orientingmeans 40. By orienting the individual particles, the magnetic particles3 can be caused to form a strong magnetic surface. The coated substrate12 then moves along in the process, optionally being preheated withpre-heater 50, and optionally acquiring upper substrate 32 prior toentering into nip 20 of heated rollers 22 and 24, whereby the mixture onthe substrate is heated, subjected to pressure, and cooled to produce aflexible magnetic composite web having oriented magnetic particles 3thereon.

[0035] Although the present invention has been described with respect toone or more particular embodiments, it will be understood that otherembodiments of the present invention may be employed without departingfrom the spirit and scope of the present invention. Hence, the presentinvention is deemed limited only by the appended claims and thereasonable interpretation thereof.

What is claimed is:
 1. A composite product comprising a first substrateand a bonded mixture, said bonded mixture comprising magnetizable ormagnetic particles and binder particles, wherein at least some of saidbinder particles coalesce at least some of said magnetizable or magneticparticles to each other, and to said first substrate.
 2. The compositeof claim 1, wherein said binder particles are on average smaller thansaid magnetizable or magnetic particles.
 3. The composite of claim 1,wherein at least some of said magnetizable or magnetic particles areformed of a material selected from the group consisting of iron, steel,magnetic stainless steel and 400 series stainless steel.
 4. Thecomposite of claim 1, wherein said magnetic particles are ferromagnetic.5. The composite of claim 1, further comprising a second substratelocated such that said bonded mixture is between said first substrateand said second substrate, wherein at least some of said magnetizable ormagnetic particles are coalesced by said binder particles to said secondsubstrate.
 6. The composite of claim 1, wherein said mixture furthercomprises a plurality of active particles.
 7. The composite of claim 6,wherein said active particles are selected from the group consisting of:iodinated resin, activated carbon, activated alumina, non-magnetizablemetal powders, alumina-silicates, super absorbent polymers, metaloxides, zeolites, glass beads, ceramics, diatomaceous earth, macroporouspolymers, aerogels, cellulosic materials, antimicrobial agents,fragrances, fragrant materials, glass micro fibers, titanate microfibers, starch, foamed polymer absorbents, macroporous super absorbentpolymers, macroreticulate super absorbent polymers, expanded vermiculite(perlite), carbon, anion exchange resins, cationic exchange resins,protein solids, organic acids, inorganic acids, minerals, salts oforganic acids, salts of inorganic acids, acrylic based polymers, clayminerals, metal oxihydrates, talcum, silicic acid, metal hydroxides,modified cellulose, cellulose, synthetic polymers, dyes, indicators,liquid absorbing compounds, malodor absorbing agents, molecular sieves,phosphates, biologically active agents, and a combination thereof. 8.The composite of claim 2, wherein said magnetizable particles have anaverage particle size from about 5 microns to about 5000 microns.
 9. Thecomposite of claim 8, wherein said binder particles have an averageparticle size of from about 5 microns to about 50 microns.
 10. Thecomposite of claim 1, wherein said binder particles are formed from atleast one component selected from the group consisting of: thermoplasticmaterials, thermoset materials, and a combination thereof.
 11. Thecomposite of claim 5, wherein said first substrate, said secondsubstrate, or a combination thereof is a metal foil, metal screen, metalmesh, or a combination thereof.
 12. A method for producing amagnetizable or magnetic composite comprising the steps of applying amixture of magnetizable or magnetic particles and binder particles to afirst substrate, applying heat to said mixture on said first substrate,and applying pressure to said mixture and said first substrate such thatsaid binder particles coalesce said magnetizable or magnetic particlesto themselves, and to said first substrate.
 13. The method of claim 12,further comprising the step of orienting said magnetic particles in amagnetic field prior to coalescing said magnetic particles with saidbinder particles.
 14. The method of claim 12, wherein said magnetizableparticles are magnetized after application of said particles to saidfirst substrate.
 15. The method of claim 12, wherein said compositeadditionally comprises a second substrate, wherein said second substrateis placed upon said mixture prior to said application of pressure,wherein said binder particles coalesce said magnetizable particles, saidfirst substrate, and optionally said second substrate.
 16. A method ofusing the composite of claim 1, comprising the step of placing saidcomposite on, under, adjacent to, or attached to, a surface to provide amagnetic property associated with that surface.
 17. The method of claim16, wherein the surface is one of a horizontal surface or a verticalsurface.
 18. The method of claim 16, wherein the surface is one of ashelf, a drawer, a cabinet, a wall or wall panel, a display board, and aroom dividing partition.